1. Field of the Invention
The present invention relates to a semiconductor integrated circuit for processing a digital signal of an optical disk of a write-once type, i.e., a compact disk of a write-once type and a semiconductor device having this semiconductor integrated circuit. The present invention also relates to a controller for controlling rotation of the optical disk of a write-once type. Further, the present invention relates to a circuit for processing a digital signal of the optical disk of a write-once type.
2. Description of the Related Art
Recently, a compact disk for audio has been used as an optical memory medium using a laser in many cases. An analog record is being replaced with a compact disk.
In general, a so-called CD-ROM is used as a memory medium of digital data. This CD-ROM is used to record and reproduce data of a computer, etc. by utilizing a compact disk in a region of a magnetic memory used as a large capacity memory. This CD-ROM can record data of a computer, a still picture, graphs, etc., in an audio signal region while compatibility of the compact disk for audio and an audio system is held. The CD-ROM has a recordable capacity of 540M bytes. Similar to the compact disk for audio, the CD-ROM is used for a large amount of copies and wide distribution.
As mentioned above, the compact disk for audio and the CD-ROM used in electronic publication, etc. are used as the general compact disk. The compact disk for audio and the CD-ROM are of a read only memory (ROM) type for only reading, etc. A maker for manufacturing the compact disk records information onto the compact disk in advance. Many decoders and reproducing devices for reproducing this compact disk are manufactured by various kinds of makers. These reproducing devices are used for only reproduction of data and have no structure for writing data.
An optical disk of a write-once type satisfying a standard of the compact disk has been recently proposed. Further, a so-called orange book standard for making a format for recording and reproducing data with respect to this write-once type disk has been also proposed.
As mentioned above, a maker for manufacturing the compact disk generally records data onto the compact disk so that a dedicated recorder for recording these data onto the compact disk is large-sized.
Further, as mentioned above, decoders and reproducing devices for the general compact disk are used for only reproduction, etc. It is difficult to arrange the dedicated recorder used by the maker of the compact disk in the decoders and the reproducing devices for only reproduction.
In a normal compact disk (CD) drive system, the user prepares all data including data of a margin bit in advance before the disk is manufactured. These data are converted to a laser pulse and are then written to the disk. However, in a drive system of the optical disk of a write-once type such as CD-WO, the user prepares only data, and it is necessary to prepare the margin bit, etc. on a drive system side. Further, when data are written to the optical disk at the real time, it is necessary to calculate a digital sum value (DSV) every pattern bit to extremely restrain the generation of a low frequency component of a signal. Accordingly, data must be converted to a laser pulse and written to the optical disk at a high speed as much as possible.
Therefore, it is necessary to store all data for making the margin bit to a ROM and hold these data wi thin an integrated circuit. Further, it is necessary to optimize an electric circuit combined with the integrated circuit and process these data by this electric circuit at a high speed.